80/20 endurance have free maintenance plans on their website:
https://www.8020endurance.com/plans/run-plans/?fwp_plan_type=maintenance
I started one of their plans after my marathon, having already done a Fitz plan and knowing the rhythm. They're based on HR monitoring and the 80/20 principle, if you're into that. Not everyone enjoys running by HR. My two cents is that, even if their plans are named after the principle that put Matt Fitzgerald on the map, I don't feel their plans are laidback... So do I like their plans? Yes. Do I love them? No. They're free, so I had nothing to lose by trying one again